com.google.dart.server.internal.remote.ByteResponseStream.java Source code

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Here is the source code for com.google.dart.server.internal.remote.ByteResponseStream.java

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/*
 * Copyright (c) 2014, the Dart project authors.
 * 
 * Licensed under the Eclipse Public License v1.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 * 
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */
package com.google.dart.server.internal.remote;

import com.google.gson.JsonObject;
import com.google.gson.JsonParser;
import com.google.gson.JsonSyntaxException;

import java.io.*;
import java.nio.charset.StandardCharsets;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;

/**
 * An {@link InputStream} based implementation of {@link ResponseStream}. Each line must contain
 * exactly one complete JSON object.
 * 
 * @coverage dart.server.remote
 */
public class ByteResponseStream implements ResponseStream {
    private class LinesReaderThread extends Thread {
        public LinesReaderThread() {
            setName("ByteResponseStream.LinesReaderThread");
            setDaemon(true);
        }

        @Override
        public void run() {
            while (true) {
                String line;
                try {
                    line = reader.readLine();
                } catch (IOException e) {
                    line = null;
                }
                // check for EOF
                if (line == null) {
                    lineQueue.add(EOF_LINE);
                    return;
                }
                // debug output
                if (debugStream != null) {
                    debugStream.println(System.currentTimeMillis() + " <= " + line);
                }
                // ignore non-JSON (debug) lines
                if (!line.startsWith("{")) {
                    continue;
                }
                // add a JSON line
                lineQueue.add(line);
            }
        }
    }

    private static String EOF_LINE = "EOF line";

    /**
     * The {@link BufferedReader} to read JSON strings from.
     */
    private final BufferedReader reader;

    /**
     * The {@link DebugPrintStream} to print all lines to.
     */
    private final DebugPrintStream debugStream;

    /**
     * The queue of lines.
     */
    private final BlockingQueue<String> lineQueue = new LinkedBlockingQueue<String>();

    /**
     * Initializes a newly created response stream.
     * 
     * @param stream the byte stream to read JSON strings from
     * @param debugStream the {@link PrintStream} to print all lines to, may be {@code null}
     */
    public ByteResponseStream(InputStream stream, DebugPrintStream debugStream) {
        reader = new BufferedReader(new InputStreamReader(stream, StandardCharsets.UTF_8));
        this.debugStream = debugStream;
        new LinesReaderThread().start();
    }

    @Override
    public void lastRequestProcessed() {
    }

    @Override
    public JsonObject take() throws Exception {
        String line = lineQueue.take();
        if (line == EOF_LINE) {
            lineQueue.add(line);
            return null;
        }
        try {
            return (JsonObject) new JsonParser().parse(line);
        } catch (JsonSyntaxException e) {
            // Include the line in the message so that we can better diagnose the problem
            throw new JsonSyntaxException("Parse server message failed: " + line, e);
        }
    }
}